Plate motion, crustal deformation, and earthquake occurrence processes in the northwest Sunda Arc, which includes the Indo-Burmese wedge (IBW) in the forearc and the Sagaing fault in the backarc, are very poorly constrained. Plate reconstruction models and geological structures in the region suggest that subduction in the IBW occurred in the geological past, but whether it is still active and how the plate motion between the India and Sunda plates is partitioned between motion in the IBW and Sagaing fault is largely unknown. Recent GPS measurements of crustal deformation and available long-term rates of motion across the Sagaing fault suggest that ~20 ± 3 mm/yr of the relative plate motion of ~36 mm/yr between the India and Sunda plates is accommodated at the Sagaing fault through dextral strike-slip motion. We report results from a dense GPS network in the IBW that has operated since 2004. Our analysis of these measurements and the seismicity of the IBW suggest that the steeply dipping Churachandpur-Mao fault in the IBW accommodates the remaining motion of ~18 ± 2 mm/yr between the India and Sunda plates through dextral strike-slip motion, and this motion occurs predominantly through velocity strengthening frictional behavior, i.e., aseismic slip. The aseismic motion on this plate boundary fault signifi cantly lowers the seismic hazard due to major and great interplate earthquakes along this plate boundary.

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We focus the geodynamic status of Eastern Himalayan Syntaxis with reference to Tibetan Plateau,Chinaand Burmese Arc using the crustal deformation constraints with GPS observation. We have used the GPS data, surface geomorphic constraints and compared the existing Pn velocity and Anisotropy [1], determined the crustal velocity of Tibetan Block and North andEast Chinablock as 2 - 8 mm/yr and 6 - 11 mm/yr considering the EHS as stable block. The lack of crustal deformation studies in EHS poses a gap in its geodynamic setup. The present attempt is first time in EHS to estimate crustal deformation by GPS. We presented GPS results from 10 stations along with one permanent station covering the EHS 2 - 3 mm/yr with an azimuth of N460. It reveals that the EHS is moving very slow rates, which accommodates the maximum strain (after Great Earthquake of8.7 M, Arunachal China Border 1950). The neotectonic activities are recorded along the major rivers traversing EHS follow the major thrusts and faults.

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